A student in a class of aspiring security guards at a vocational school in Los Angeles walked out of the room, then returned to shoot his instructor dead, according to investigators. Police busted the 22-year-old suspect afterward as he stood on the street smoking a cigarette, the Los Angeles Times reports. The victim was shot multiple times at close range, and one of the other 13 students in the class was injured. The instructor "was one of the nicest guys ever," a witness said. "It was just a random act." Police are seeking a motive and interviewing witnesses.